Extracellular enzymes as well as biofilm inhibiting compounds producing Bacillus tequilensis was evaluated for its probiotic effect on the growth and survival of shrimp Penaeus vannamei larvae under biofloc system. Growth and survival was significantly higher (p<0.05) in probiotic supplemented treatments and especially in probiotic customized biofloc system. Biofloc system generally maintained the optimum water quality level and the addition of probiotic strains enhanced it more effectively.
The heterotrophic bacterial population was significantly high (p<0.05) in probiotic supplemented groups. The extracellular enzyme activities such as amylase, protease and lipase were screened and it was found to be high in probiotic supplemented groups. The mRNA expression of the immune related genes was upregulated in the shrimps reared in bioflocs customized with probiotic strain. The proteomic variation in muscle tissue from the control and probiotic supplemented shrimps reared in biofloc system was determined by using 2D electrophoresis and further MALDI-TOP analysis. Highly significant increase in abundance of Daxx OS protein was found in probiotic supplemented shrimps and in addition to this Lit v 1 tropomyosin expression was also observed high in probiotic supplemented biofloc groups. Both the proteins playing significant role in avoiding viral and bacterial especially Vibrio infection. The results concluded that the biolfoc system is an advantageous technology for preventing the pathogenic diseases through the expression of important proteins.